Method for determining at least a partial
movement pattern of a dental treatment instrument (14), in particular a
toothbrush, resulting during dental treatment, in particular tooth cleaning, comprising at least the following steps: Acquisition of data by means of at least one optical acquisition device (4) relating to at least one movement parameter of the dental treatment device (14) which is moved in at least one X / Y plane for the treatment of surface parts of the teeth relative to a first reference
system which moves with the head of the person being treated (8) wherein the optical acquisition device is designed as at least one camera for the three-dimensional acquisition of the at least one movement parameter of the dental treatment device, wherein at least one or both pupils and / or the
nose of the person being treated are located in a detection area of the camera, wherein a processor device (2) defines a further three-dimensional reference
system that moves with the dental treatment device (14) when the dental treatment device (14) is moved in space, wherein the reference
system is formed by characteristic anthropometric body points,
body lines and / or body surfaces of the hand with which the dental treatment device (14) is guided, and providing the acquired data to a processor device (2) for determining the
movement pattern, wherein the movement of the dental treatment device is recorded relative to the first reference system coupled with a movement of the head, the dental treatment device is an electric
toothbrush, wherein the processor device is a
mobile phone or a
tablet PC and wherein the processor device includes the optical detection device.